Trimercurated acetaldehyde as the mercuration product of ethanol. The crystal structure of (ClHg)3CCHO·DMF and (BrHg)3CCHO·DMSO

The product obtained by boiling an ethanolic solution of mercuric chloride with sodium acetate (Hofmann, 1899) has been identified as tris(chloromercuri)acetaldehyde. The analogous bromomercuri derivative is obtained by using mercuric bromide. Both compounds crystallize from DMSO of DMF solution as the one-to-one solvates. The crystal structure of (ClHg)₃CCHO·DMF (A) and (BrHg)₃CCHO·DMSO (B) has been determined by X-ray diffraction methods and refined by full-matrix least-squares to the conventional R indices of 0.087 and 0.079, respectively. The mean value of the HgC bond length is 2.09(9) Å in A and 2.04(7) Å in B.     

Two furan‐2,5‐dicarboxylic acid solvates crystallized from dimethylformamide and dimethyl sulfoxide

Furan‐2,5‐dicarboxylic acid (FDCA) has been ranked among the top 12 bio‐based building‐block chemicals by the Department of Energy in the US. The molecule was first synthesized in 1876, but large‐scale production has only become possible since the development of modern bio‐ and chemical catalysis techniques. The structures of two FDCA solvates, namely, FDCA dimethylformamide (DMF) disolvate, C₆H₄O₅·2C₃H₇NO, (I), and FDCA dimethyl sulfoxide (DMSO) monosolvate, C₆H₄O₅·C₂H₆OS, (II), are reported. Solvate (I) crystallizes in the orthorhombic Pbcn space group and solvate (II) crystallizes in the monoclinic P space group. In (I), hydrogen bonds form between the carbonyl O atom in DMF and a hydroxy H atom in FDCA. Whilst in (II), the O atom in one DMSO molecule hydrogen bonds with hydroxy H atoms in two FDCA molecules. Combined with intermolecular S…O interactions, FDCA molecules form a two‐dimensional network coordinated by DMSO.     

Some Reactions of gem‐Dibromocyclopropanes and Metal Carbonyls

A series of gem‐dibromocyclopropanes were treated with various metal complexes. Among the metal complexes, Ru(CO)₂(PPh₃)₃, Ru(CO)₃(PPh₃)₂, and Mo(CO)₆ were able to remove a bromine atom from 1,1‐dibromo‐2‐phenylcyclopropanes ( 1 ) to yield a series of corresponding of 1‐bromo‐2‐phenylcyclopropanes ( 2 ). Upon the treatment of 1 with Cr(CO)₆ in DMSO, a series of allenes were obtained in good yields. The correlation between the rate of formation of allenes and the substituents on the benzene gives a negative coefficient which suggests the dibromocyclopropanes possesses as an electrophile toward to Cr(CO)₆. In the presence of Cr(CO)₆, gem‐dibromobicyclo[n,1,0]alkanes ( 4 ) in DMF or DMSO solution underwent the cleavage of carbon‐bromine bond followed by ring‐expansion and coupling reaction to form bicycloalkenes 7 .     

Spectrophotometric study of uranium(VI) complex equilibria with N,N-dimethylformamide

Spectrophotometric study of solvation equilibria of uranium(VI) with N,N-dimethyl formamide (DMF) in solutions with ionic strength I = 3.0 mol^.dm^-3 (Na, H)ClO₄ shows that DMF forms with UO₂ ²⁺ several relatively stable solvates absorbing in VIS range (350-490 nm). The absorbance of UO₂ ²⁺ bands increases and their absorption maxima shift to longer wavelengths while uranyl solvates are formed stepwise with increasing concentration of DMF. Areas of prevailing existence of individual solvates with stoichiometry 1 : n (n = 1, 2, 4, 6) have been found and their stability constants and molar absorption coefficients estimated using both graphical methods and computer minimization programs.     

Solvent-induced <Emphasis Type="Italic">E/Z</Emphasis>(C=N)-isomerization of imines of some hydroxy-substituted formylcoumarins

Aromatic imines, namely, 5-formyl-6-hydroxy-4-methyl- and 8-formyl-7-hydroxy-4-methylcoumarin derivatives, have been synthesized. A dependence of their spectral characteristics (¹H NMR spectra, electronic absorption spectra) from the solvent (DMSO, CHCl₃, DMF, acetonitrile, MeOH) has been studied. The solvatochromic effects observed for a number of imines, first of all, for 7-hydroxy-4-methyl-8-(4′-nitrophenylimino)methyl-2H-1-benzopyran-2-one, were related to their E/Z-isomerization with respect to the C=N bond based on the quantum chemical calculations by the AM1, PM3, PPP CI methods. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1954–1960, September, 2008.     

Kinetics and reactivity of substituted anilines with 2‐chloro‐5‐nitropyridine in dimethyl sulfoxide and dimethyl formamide

The kinetics of the reaction of substituted anilines with 2‐chloro‐5‐nitropyridine were studied in dimethyl sulfonide (DMSO) and dimethyl formamide (DMF) at different amine concentrations and temperatures in the range 45–60°C. In both solvents the reaction was not a base‐catalyzed one. A plot of ΔH^# versus ΔS^# for the reaction in DMSO and DMF gave good straight lines with isokinetic temperatures 128°C and 105°C, respectively. Good linear relationships were obtained from the plots of log k₁ against σ° values at all temperatures with negative ρ values (?1.63 to ?1.28 in DMSO) and (?1.26 to ?0.90 in DMF). © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 645–650, 2002     

Der erste sechsgliedrige Zinn(II)-Übergangsmetallzyklus – [Mn(CO)4SnCl(DMF)]3

First Compound with a Six-Membered Tin(II) Transition Metal Ring – [Mn(CO)₄SnCl(DMF)]₃ Tin(II) chloride and dimanganese decacarbonyl were reacted in dimethyl-(DMF) at 150°C or monomethylformamide (MMF) at 120°C to yellow product solvates of the type [Mn(CO)₄SnCl(D)]₃ (D = DMF and MMF). Their identification in the case of the compound [Mn(CO)₄SnCl(DMF)]₃ was undertaken by a single crystal X-ray analysis. As result of this determination, its central molecular fragment contained a non-planar (SnMn)₃ ring with the following average bond parameters: Sn? Mn bond lengths of 258.8(5) pm, endocyclic bond angle at Mn Atom of 90.5(2)° and the corresponding angle at Sn atom of 141.6(2)°. After the result of ¹¹⁹Sn Mößbauer spectroscopic measurements of the title substance a tin(II) oxidation state was present. The ν(CO) i.r. absorption bands and ¹H n.m.r. data of both obtained products were measured for a further characterization. With view to the mechanistic pathway of the product formation, it was ascertained by separate experiments that the postulated intermediate Cl₃SnMn(CO)₅ and tin(II) chloride in DMF solution produced the title compound.     

Reactivity of 3d-metal salt solvates in reactions with porphyrins: Influence of the trans effect

The reactivity of 3d-metal salt solvates [MX₂(S)₄] and [MX₂(S₁) _m (S₂)_4?m ] has been studied in reactions with different porphyrins: meso-tetraphenylporphine (H₂TPP), N-methyloctaethylporphine (H(N-Me)(β-Et)₈P), and meso-tetraphenyltetrabenzoporphine (H₂TBP(ms-Ph)₄). Solvents S, S₁, and S₂ are dimethyl sulfoxide (DMSO), dimethylformamide (DMF), and pyridine (Py), respectively. The strong catalytic effect of the solvents and ligands with π orbitals on the reaction rates due to the trans influence in the coordination sphere of the salt solvates has been observed and explained. A possible activation mechanism of the trans influence was considered. A strong dependence of the trans effect on the nature of the metal and porphyrin was shown.     

Crystal Engineering Using Polyiodide Halogen and Chalcogen Bonding to Isolate the Phenothiazinium Radical Cation and Its Rare Dimer, 10-(3-Phenothiazinylidene)phenothiazinium

Utilizing facile one-electron oxidation of 10H-phenothiazine by molecular diiodine, the solid-state structure of the 10H-phenothiazinium radical cation was obtained in three cation:iodide ratios, as well as its THF and acetone solvates. Oxidation of 10H-phenothiazine with molecular diiodine in DMSO or DMF provided the structure of the radical coupling product 10-(3-phenothiazinyldene)phenothiazinium, which has not been crystallographically characterized to date. The radical cations were balanced by a mixture (I₇)⁻, (I₅)⁻, (I₃)⁻, and I⁻ anions, where a variety of chalcogen, halogen, and hydrogen bonding interactions stabilize the structures to reveal these interesting cationic species.     

Oxidation of secondary alcohols byN-methylmorpholine-N-oxide (NMO) catalyzed by Ru(II) halosulfoxide complexes. A kinetic study

RuX₂(DMSO)₄ (X=Cl,cis; Br,trans) undergoes ligand substitution in N,N-dimethylformamide (DMF) to give RuX₂(DMSO)₃DMF, which catalyzes the oxidation of secondary alcohols by NMO to ketones. Kinetics of the reaction catalyzed bytrans-RuBr₂(DMSO)₄ differed from that ofcis-RuCl₂(DMSO)₄. A mechanism is proposed involving the formation of Ru(IV)oxo species as the active intermediate and a rate expression is derived.     

CO2 on a Tightrope: Stabilization,Room‐Temperature Decarboxylation,and Sodium‐Induced Carboxylate Migration

A sterically shielded 3‐substituted zwitterionic N,N‐dimethylisotryptammonium carboxylate has been synthesized by consecutive chemoselective double alkylation of indole. The carboxylate undergoes a quantitative and unusually facile decarboxylation in dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF) at room temperature. The breaking of a nearly equidistant hydrogen bond by solvent molecules initiates heterolytic C? C cleavage. The decarboxylation rate decreases with increasing CO₂ partial pressure, proving the competitiveness of protonation and re‐carboxylation of the carbanionic intermediate. Corresponding spiro compounds containing silylene and stannylene moieties show high thermal stability. Addition of an excess of methyllithium to the sodium salt triggers a reaction sequence comprising a deprotonation, carboxylate transfer, and nucleophilic trapping of the rearranged carboxylate by another equivalent of methyllithium. Hydrolytic work‐up of the geminal diolate leads to an acetyl product. The role of the sodium counterion and the mechanism of the rearrangement have been unraveled by deuteration experiments.     

Manipulation of Molecular and Supramolecular Structure in Cobalt(II) Complexes with Tetrachloroterephthalate through the Influence of Different Solvents

The reactions of cobalt acetates with tetrachloroterephthalic acid (H₂BDC‐Cl₄) in different solvents gave two polymeric and one mononuclear Co^II complexes. X‐ray single‐crystal structural determination revealed that the ligand BDC‐Cl₄ displays a reliable bridging tecton to construct diverse supramolecular architectures through coordinative bonds or secondary hydrogen‐bonding interactions. The complexes [Co(BDC‐Cl₄)(DMF)₂(EtOH)₂]_n ( 1 ) and {[Co(BDC‐Cl₄)(DMF)₂(MeOH)₂] · 2DMF}_n ( 2 ) demonstrate a one‐dimensional (1D) coordination motif with infinite Co^II‐tetrachloroterephthalate chains, which are tuned by different binding solvent systems of DMF/ethanol (EtOH) and DMF/methanol (MeOH). [Co(DMF)₂(H₂O)₄] · (BDC‐Cl₄) ( 3 ) represents a two‐dimensional (2D) metallosupramolecular network by hydrogen‐bonded bridging between the aqua ligand of the mononuclear complex with the uncoordinated BDC‐Cl₄ solvates. The spectroscopic, thermal, and fluorescent properties of 1 – 3 were also investigated.     

Poly[diaqua­hexa­kis­(dimeth­yl sulfoxide‐κO)cerium [(μ2‐hexa­cosa­oxoocta­molybdate)sodium]]

The title compound, {[Ce(C₂H₆OS)₆(H₂O)₂][NaMo₈O₂₆]}_n, contains an infinite chain of β‐octa­molybdate moieties linked by Na⁺ ions, and further linked into a two‐dimensional network by [Ce(DMSO)₆(H₂O)₂]³⁺ (DMSO is dimethyl sulfoxide) groups via hydrogen‐bond inter­actions. The Ce and Na atoms are located on a twofold axis and an inversion centre, respectively.     

Syntheses and Structures of Three New Copper(II) Coordination Polymers Involving 2, 2‐(4, 6‐Dinitro‐1, 3‐phenylenedioxy)­diacetic Acid

Three copper(II) coordination polymers, namely, {[CuL(H₂O)₂] · 4H₂O}_n( 1 ), [CuL(H₂O)(DMF)]_n( 2 ), and [CuL(2, 2′‐bipy)(DMSO)] · DMSO ( 3 ) [H₂L = 2, 2′‐(4, 6‐dinitro‐1, 3‐phenyl‐enedioxy)diacetic acid] were synthesized in different solvents (H₂O, DMF, and DMSO). X‐ray single crystal diffraction studies show that both complexes 1 and 3 belong to triclinic crystal system and P$\bar{1}$ space group and complex 2 belongs to the monoclinic crystal system and P2₁/c space group. In three complexes, all the central Cu^II ions coordinate with the ligand, forming a square pyramidal configuration. Both complexes 1 and 2 show similar 1D chain‐like structure and the chains are further connected by hydrogen bonds, forming 3D frameworks. Complex 3 exhibits a 0D structure due to the introduction of the ligand 2, 2′‐bipy. In addition, the luminescence properties of these complexes were investigated.     

The Structure of cis‐[Chloro(dimethylsulfoxide)bis(1, 10‐phenanthroline)ruthenium(II)]‐tetraphenylborate, [RuCl(DMSO)(1, 10‐phen)2][BPh4]

The complex cis‐[RuCl(DMSO)(phen)₂]BPh₄, where DMSO is dimethylsulfoxide and phen is 1, 10‐phenanthroline, crystallizes in the monoclinic space group P2₁/c with a = 19.505(4), b = 10.045(2), c = 21.199(4) Å, β = 90.137(4)°, V = 4153(2) ų, Z = 4, D_calc = 1.430 g cm^—3. The ruthenium coordination geometry is that of a slightly distorted octahedron with a cis‐RuN₄ClS arrangement of the ligand donor atoms. The Ru—Cl distance is 2.421(1) Å and the Ru—S distance 2.250(2) Å. The four Ru—N distances are 2.057(6), 2.066(4), 2.073(4), and 2.086(4) Å with the Ru—N bond trans to Cl the second shortest and the Ru—N bond trans to S the longest one.     

Structure and electrospray mass spectrometry studies on dithiacyclooctan-3-ol-containing palladium (II) complex of trans -[Pd(dtco-3-OH)_2](ClO_4)_2·2DMSO

The structure of trans-[Pd(dtco-3-OH)2] (ClO4)2·2DMSO, in which dtco-3-OH is dithiacyclooctan-3-ol and DMSO is dimethyl sulfoxide, was determined by X-ray crystallographic analysis. The crystal data: space group pi, a = 0.7077(2) nm, b = 1.0788(1) nm, c = 1.1111(1) nm, α=67.710(8)°, β = 73. 59(2)°, γ = 85. 39(2)°,R1 = 0 . 0368 and Rw = 0.0998. The palladium (II) is coordinated by four sulfur atoms with a regular square planar configuration. The Pd-S distances are 0.2314(1) and 0.2317(1) nm, respectively. Both dtco-3-OH ligands are in the boat-chair configuration and two hydroxyl groups are on the opposite sites of the PdS4 coordination plane and are towards Pd(II). The Pd-O distance is 0. 285 nm, indicating a weak interaction between them. A typical hydrogen bond between the hydroxyl group of dtco-3-OH ligand and DMSO was observed in the crystal structure. An aqueous solution prepared with the crystals of the complex was used for the investigation of electrospray mass spectrometry ( ESMS ). Besid     

Attachment of anthraquinone derivatives to glassy carbon and the electrocatalytic behavior of the modified electrodes toward oxygen reduction

The electrochemical reduction of oxygen on glassy carbon (GC) electrodes modified with anthraquinones was studied using cyclic voltammetry (CV) and the rotating disk electrode (RDE) technique. Two methods were used in surface modification. The first method comprised immersion of the polished or anodically pretreated GC electrode in a solution containing 9,10-anthraquinone-2-carboxylic acid (AQ-2-COOH) or its anion (AQ-2-COO⁻) in dimethylsulfoxide (DMSO) or 9,10-anthraquinone-2-ethanoic acid (AQ-2-CH₂COOH) or its anion (AQ-2-CH₂COO⁻) in N,N-dimethylformamide (DMF). Alternatively, the surface of the GC disk was modified by anodic oxidation of AQ-2-COOH or AQ-2-COO⁻ in DMSO or AQ-2-CH₂COOH in DMSO or DMF or AQ-2-CH₂COO⁻ in DMF. The modified electrodes showed electrocatalytic activity toward oxygen reduction in 0.1 M acetate buffer pH (4.8), 0.1 M phosphate buffer (pH 8) and 0.1 M NaOH. Atomic force microscopy (AFM) examination of the modified electrodes was carried out and the differences in surface morphology of various modifications were in evidence.     

Isolation,Purification and Characterization of a Surfactants-, Laundry Detergents- and Organic Solvents-Resistant Alkaline Protease from <Emphasis Type="Italic">Bacillus</Emphasis> sp. HR-08

Bacillus sp. HR-08 screened from soil samples of Iran, is capable of producing proteolytic enzymes. 16S rDNA analysis showed that this strain is closely related to Bacillus subtilis, Bacillus licheniformis, Bacillus pumilus, Bacillus mojavensis, and Bacillus atrophaeus. The zymogram analysis of the crude extract revealed the presence of five extracellular proteases. One of the proteases was purified in three steps procedure involving ammonium sulfate precipitation, DEAE-Sepharose ionic exchange and Sephacryl S-200 gel filtration chromatography. The molecular mass of the enzyme on SDS-PAGE was estimated to be 29 kDa. The protease exhibited maximum activity at pH 10.0 and 60 °C and was inhibited by PMSF but it was not affected by cysteine inhibitors, suggesting that the enzyme is a serine alkaline protease. Irreversible thermoinactivation of enzyme was examined at 50, 60, and 70 °C in the presence of 10 mM CaCl₂. Results showed that the protease activity retains more than 80% and 50% of its initial activity after incubation for 30 min at 60 and 70 °C, respectively. This enzyme had good stability in the presence of H₂O₂, nonionic surfactant, and local detergents and its activity was enhanced in the presence of 20% of dimethyl sulfoxide (DMSO), dimethyl formamide (DMF) and isopropanol. The enzyme retained more than 90% of its initial activity after pre-incubation 1 h at room temperature in the presence of 20% of these solvents. Also, activation can be seen for the enzyme at high concentration (50%, v/v) of DMF and DMSO.     

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide is described. In the reaction with allyl bromide, either a Pd(dba)₂? CuI combination (dba, dibenzylideneacetone) in DMF or copper(I) iodide in DMSO–THF readily catalyzes or mediates the coupling reaction of (Z)‐silyl(stannyl)ethenes at room temperature, producing novel vinylsilanes bearing an allyl group β to silicon with cis ‐disposition in good yields. Allyl chlorides as halides can be used in the CuI‐mediated reaction. CuI alone much more effectively mediates the cross‐coupling reaction with propargyl bromide in DMSO–THF at room temperature compared with a Pd(dba)₂? CuI combination catalysis in DMF, providing novel stereodefined vinylsilanes bearing an allenyl group β to silicon with cis ‐disposition in good yields. Copyright © 2008 John Wiley & Sons, Ltd.     

Solvated and solvent‐free forms of N,N′‐di­thio­diphthal­imide

N,N′‐Di­thio­diphthal­imide, C₁₆H₈N₂O₄S₂, crystallizes from ethyl acetate with two independent mol­ecules in the asymmetric unit, in which the N—S—S—N torsion angles are ?83.59 (19) and 92.9 (2)°. The mol­ecules are linked by C—H?O hydrogen bonds and aromatic π–π‐stacking interactions into a three‐dimensional framework. When crystallized from either di­chloro­methane or ethanol, solvates are formed in which the mol­ecules of the title compound lie across twofold rotation axes in space group C2/c, with N—S—S—N torsion angles of 93.54 (7) and 96.14 (11)°. There are no hydrogen bonds in these solvates, but the mol­ecules are linked by aromatic π–π‐stacking interactions into chains, between which there are continuous channels. Disordered solvent mol­ecules occupy these channels, which account for ca 20% of the unit‐cell volume.